UPDATE 8:45 p.m. ET: Carrie Fisher's brother, Todd, told Entertainment Tonightthat his sister is in the intensive care unit of the hospital where she is "being well looked after." "If everyone could just pray for her, that would be good," he told ET. "The doctors are doing their thing and we don't want to bug them. We are waiting patiently."

Todd added that Carrie's condition is unknown. "We don't know. We hope for the best," he said. "We certainly do not know her condition — that's why she is in ICU. I'm sure everyone wants to speculate, but now is not the time for that."

UPDATE 7:02 p.m. ET: Carrie Fisher's brother,Todd, told theAssociated Press that she's "out of emergency" and stabilized at the hospital. Her daughter, Billie Lourd, and her beloved dog, Gary, are also by her side, according to TMZ.

UPDATE 5:49 p.m. ET: Paramedics reportedly performed CPR on Carrie Fisher for 15 minutes until they were able to get a pulse, TMZ reports. The actress is currently on a ventilator at UCLA Medical Center.

UPDATE: According to theLos Angeles Times, Fisher is in critical condition at a Los Angeles hospital.A source, who was not authorized to discuss the incident, told the paper that the actress was "in a lot of distress on the flight." According to TMZ, United Airlines says its crew reported Fisher as "unresponsive" when they landed.

In a statement posted by the Los Angeles Fire Department, the LAFD "responded to LAX International Airport, Gate 74, for a patient on an inbound flight in cardiac arrest. LAFD firefighter paramedics were standing by for the plane's arrival, provided advanced life support and aggressively treated and transported the patient to a local hospital."

Carrie Fisher on Dec. 16, 2015, in London.Karwai Tang/WireImage

Original story continues below:

Carrie Fisher suffered a massive heart attack while on a flight from London to LAX on Friday, December 23.

Actor Brad Gage was on the flight and witnessed the health scare. "I'm in complete shock. @AnnaAkana and I sat in front of Carrie Fisher on our flight from London and she was just taken off the plane by EMTs," he tweeted Friday afternoon. Actress Anna Akana was also on the flight and tweeted that Fisher "wasn't breathing for 10 minutes or so" and that "they were administering CPR up until we landed."

Harrison Ford, who played Han Solo in the original Star Wars films, told The Hollywood Reporter on Saturday, December 24: "I'm shocked and saddened to hear the news about my dear friend. Our thoughts are with Carrie, her family and friends."

Actor Peter Mayhew, who plays Chewbacca, also sent his thoughts and prayers to his Star Wars costar.

Thoughts and prayers for our friend and everyone's favorite princess right now.. @carrieffisher